Field
This disclosure relates to communication networks. More specifically, this disclosure relates to a system and method for extending virtualized networks.
Related Art
The exponential growth of the Internet has made it a popular delivery medium for a variety of applications running on physical and virtual devices. Such applications have brought with them an increasing demand for bandwidth. As a result, equipment vendors race to build larger and faster switches with versatile capabilities, such as network virtualization and multi-tenancy, to accommodate diverse network demands efficiently. However, the size of a switch cannot grow infinitely. It is limited by physical space, power consumption, and design complexity, to name a few factors. Furthermore, switches with higher capability are usually more complex and expensive. More importantly, because an overly large and complex system often does not provide economy of scale, simply increasing the size and capability of a switch may prove economically unviable due to the increased per-port cost.
A flexible way to improve the scalability of a switch system is to build a fabric switch. A fabric switch is a collection of individual member switches. These member switches form a single, logical switch that can have an arbitrary number of ports and an arbitrary topology. As demands grow, customers can adopt a “pay as you grow” approach to scale up the capacity of the fabric switch.
Meanwhile, layer-2 and layer-3 (e.g., Ethernet and Internet Protocol (IP), respectively) switching technologies continue to evolve. IP facilitates routing and end-to-end data transfer in wide area networks (WANs) while providing safeguards for error-free communication. On the other hand, more routing-like functionalities are migrating into layer-2. Notably, the development of the Transparent Interconnection of Lots of Links (TRILL) protocol allows Ethernet switches to function more like routing devices. TRILL overcomes the inherent inefficiency of the conventional spanning tree protocol, which forces layer-2 switches to be coupled in a logical spanning-tree topology to avoid looping. TRILL allows routing bridges (RBridges) to be coupled in an arbitrary topology without the risk of looping by implementing routing functions in switches and including a hop count in the TRILL header.
As Internet traffic is becoming more diverse, network virtualization is becoming progressively more important as a value proposition for network architects. In addition, the evolution of virtual computing has made multi-tenancy attractive and, consequently, placed additional requirements on the network. For example, virtual servers are being allocated to a large number of tenants while a respective tenant operates multiple virtualized networks. It is often desirable that the network infrastructure can provide a large number of virtualized network to support multi-tenancy and ensure network separation among the tenants.
While today's networks support many desirable features, some issues remain unsolved in efficiently facilitating virtualized networks across multiple networks.